Since the flexible electronic device has several superior characteristics such as lightness, flexibility, endurance from high impact, safety, and portability, the flexible electronic device is becoming the mainstream device for the next generation. Generally speaking, the method of fabricating the electronic device over a flexible substrate requires attaching the flexible substrate over a rigid substrate by first employing an adhesion layer. Next, the electronic device is fabricated on the flexible substrate, where the flexible substrate is attached on the rigid substrate directly. Finally, after electronic devices are fabricated on the flexible substrate it is then separated from the rigid substrate.
However, the flexible substrate usually has a higher thermal expansion coefficient (CTE), so the flexible substrate inflates or shrinks according to the change of the environmental temperature during the process of fabricating the flexible electronic device. Especially, when CTE mismatch between the rigid substrate and the flexible substrate occurs it may further cause stress on the fabricated electronic device. Therefore, in order to fabricate electronic device such as the thin film transistor over the flexible substrate, it is necessary to overcome problems such as poor alignment accuracy and the processing temperature limitations.